The present invention relates to the recovery of hydrcarbons from petroleum reservoirs, and particularly, the engineering of stimulated recovery processes. The term stimulated recovery process is used to describe both secondary recovery processes, such as water floods, steam floods, and others, as well as tertiary recovery processes, such as chemical floods and miscible floods. Also, the method of the present invention can be used in studying any primary production of a reservoir.
In most reservoir engineering studies of stimulated production of hydrcarbon reservoirs, a mathematical simulation of the reservoir is developed. Mathematical simulation defines the fluid saturation in terms of gas, oils, and perhaps water at various positions and times within the reservoir. The simulation may also determine the temperatures at various locations and times within the reservoir as well as the pressures at the various locations and times in the reservoir. Several methods for constructing mathematical simulations of reservoirs have been described in the literature. For example, the recent book entitled "Modern Reservoir Engineering--A Simulation Approach" by Henry B. Crichlow, published by Printice-Hall, Inc., Englewood Cliffs, N.J. 07632, describes the steps required to develop a mathematical simulation of a reservoir subject to various recovery processes.
In order to construct a mathematical simulation of the reservoir, it is necessary to know the porosity and permeability of the reservoir as well as the areal extent of the reservoir and the locations of the various wells that are used as injection wells and producing wells. Normally, this information is available from the original logs of the wells and subsequent production of the reservoir. Using this information and other related data, it is possible to construct a mathematical simulation of the reservoir.
The accuracy of the mathematical simulation of a reservoir can then be checked against the history of the reservoir after it is subjected to the simulated recovery process. The production history of the reservoir will allow the engineer to refine his mathematical simulation, and with the refined mathematical simulation, predict the future performance of the reservoir and locate possible problem areas.
While the above approach to reservoir engineering is well-known, several problems confront the engineer. For example, while the mathematical simulation will provide the distribution of reservoir parameter values throughout the reservoir at any particular time, this distribution has been typically displayed in the form of (1) arrays of numbers or (2) a line-printed plot from a computer printer or (3) output from off-line plotters. Of course, these plots are only two-dimensional plots and will represent either the distribution of reservoir parameter values over an areal extent of the reservoir or along a surface which is substantially vertical to the reservoir formation. While plots can be constructed for any point in time, it is difficult to analyze these plots to detect the location of problem areas or to analyze how rapidly events are taking place in the reservoir. These difficulties are caused primarily by the fact that each plot is a static display and the change from one plot to the succeeding plot is very small if relatively short time intervals are used. If longer time intervals are used, the changes will be shown but their development and possible cause will not be apparent.